Nissan Micra (1992 - 2003) - 98 1275 High HC PPM at MOT

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Sat 7 Nov 2009 14:47
98 1275 High HC PPM at MOT - Chris S
I've just put my Micra through the MOT - the HC was near the 200 PPM limit.

All the other emissions figures were well withing limits.

Does anyone know what caused the high HC PPM?

Can it be fixed or should I start looking for another car when the next MOT approaches?
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Sat 7 Nov 2009 18:45
98 1275 High HC PPM at MOT - elekie&a/c doctor
Tbh I would not do anything to try and reduce this figure.In simple terms the HC level represents the amount of unburnt fuel exiting the exhaust system.As the car is over 10 years old I would guess that the engine is a little down on efficiency.If the other figures are within limits then nothing to worry about.hth
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Sat 7 Nov 2009 20:22
98 1275 High HC PPM at MOT - bathtub tom
When I had this it was exhaust valves.

The car had been to a tyre place under a previous owner and they'd shimmed the valves. All the tolerances were far too tight and one exhaust valve had no gap!

I suspect they'd got their maths wrong and reduced the gaps instead of increasing them.

I had the head off, ground in the valves (one new exhaust) and re-shimmed them all correctly. It transformed the car, you could balance a pound coin on it at tickover and the low-end torque was amazing.
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